Methods for measuring sub-pm rad vertical emittance at the Swiss Light Source

We report on methods capable of measuring a rms vertical electron beam size of 3 pm with a runs error of less than 10% at a diagnostic beamline at the Swiss Light Source (SLS). This corresponds to a vertical emittance 01 06 pm rad with a 20% rms error. We showed this capability by presenting the theoretical basis for, and the data from, a series of measurements on a stable beam at 1.6 pm rad vertical emittance at the SLS. The methods presented utilized either pi- or sigma-polarized synchrotron radiation (SR) in the visible to ultra violet (vis-UV) spectral range. In addition to the established g-polarization method, we introduced a diffraction method with a potentially high resolution capability. Also an intensity imbalanced diffraction scheme was introduced, but was found to be prone to SR induced carbon contamination on optical elements. (C) 2015 Elsevier B.V. All rights reserved.